The present invention relates to an optical ruler structure in which during sliding, the abrasion of the slide seat is reduced and the internal circuits are prevented from being damaged by dirt.
FIGS. 1 and 2 show a conventional optical ruler composed of a first and a second guide seats 1, 2 which are movable relative to each other. The first guide seat 1 is fixed on one side of a working table of an automatized mother machine (not shown). A slide seat 3 is disposed in the first guide seat 1, which is reciprocally movable along with the working table. A signal outputting device 4 is disposed on upper side of the slide seat 3 for indicating the displacement of the slide seat 3. The slide seat 3 on lower side has a slide section 5 connecting with the second guide seat 2.
After a period of use, the slide section 5 of the slide seat 3 is subject to abrasion. This not only will lead to frequent replacement of the second guide seat 2, but also will affect the accuracy of the measurement.
Moreover, when the slide seat 3 is moved, the iron chips produced during cutting operation may be curved upward to damage the internal structure of the first guide seat 1 and the circuits of the signal outputting device 4 above the slide seat 3. This will make the ruler lose its accuracy.